Cache the default storage block

[abrookins]

First check

• I added a descriptive title to this issue.
• I used the GitHub search to find a similar request and didn't find it.
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Describe the current behavior

In 2.x and 3.x, we load the default storage block whenever we persist a result. This means that for every task run, we:

• Make an API request to get the block document for the default storage block
• Load all plugins from disk (because Block.load does this as a side effect)
• Hydrate the block

So a flow that runs 500 tasks does this 500 times.

Describe the proposed behavior

We should cache the default block the first time we load it, at least for a short period.

Example Use

No response

Additional context

No response